Bushings having current-limiting fuses mounted therein generally consist of a spider axially aligned in a passage in the bushing with a fusable element spirally wrapped around the spider. The passage is then filled with a granular, dielectric material such as sand. Typical of this type of structure is shown in U.S. Pat. No. 3,633,141, issued on Jan. 4, 1972, and entitled "Electrical Bushing Assembly"; U.S. Pat. No. 3,913,050, issued on Oct. 14, 1975, and entitled "Fuse Assembly for Current-Limiting Fuses"; and U.S. Pat. No. 3,648,211, issued on Mar. 7, 1972, and entitled "High Voltage Current-Limiting Protective Device." In each of these patents the current-limiting fuse ribbon is mounted on a spider located within the bushing. On interruption of the fuse, the bushing is subjected to thermal shock which often cracks the bushing.
In U.S. Pat. No. 3,911,385, issued on Oct. 7, 1985, and entitled "Outdoor Current-Limiting Fuse," a fuse structure is shown which includes a casing or tube 12 having terminal end caps and a plurality of fusable elements extending between the end caps. The fusable elements being shown in the form of wires which are suspended in the granular dielectic material. In this type of structure, difficulties have occurred in filling the tube with the granular material since the wires cannot be observed and it is not known whether the wires have shifted during filling. If the wires are too close to the walls of the housing or collapse upon each other, short circuits can occur within the fuse housing.